Base station apparatuses divide their coverage area of radio waves into a plurality of cells to control communications of a terminal device positioned in each cell using a baseband card and a unit. When the terminal device moves across cells, base station apparatuses perform a handover in the base station, such as a handover between baseband cards and a handover between units, thereby continuing the communications.
When a handover target device receives a handover start message, for example, the device starts a data transfer end monitoring timer. The device receives transfer data transferred from a handover source device while the timer is operating. When the data transfer end monitoring timer expires, the handover target device stops receiving the data and completes the handover.
Patent literature 1: Japanese National Publication of International Patent Application No. 2010-536264
Patent literature 2: International Publication Pamphlet No. WO 2008/053511
In a case where a handover in a base station apparatus occurs, the conventional technologies have low communication efficiency of transferring data received by the handover source after the handover to the handover target. This leads to delay in handover processing.
In the handover target device, for example, the data transfer end monitoring timer for each user terminal is not set. To prevent loss of transfer data in a handover, the handover target device sets a sufficient time. This possibly prevents the handover target device from finishing the handover processing because the data transfer end monitoring timer does not expire despite completion of data transfer in a case where the data transfer is small.